Radiotherapy combined with hormonal therapy after surgery significantly reduced the chance of recurrence in women with early hormone receptor-positive (HR+) breast cancer, according to results of a 10-year trial presented at the European Society for Radiotherapy and Oncology (ESTRO) 38 conference in Milan, Italy.
Results of the 8 A arm of the Australian Breast and Colorectal Cancer Study Group found cancer did not return in the same breast in 97.5% of women who underwent whole-breast irradiation (WBI) and hormonal therapy after a 10 year follow-up period. In women who only received hormonal therapy, that fraction was 92.4%.
“Our findings show that radiotherapy is still highly effective in significantly improving local control and disease-free survival in combination with anti-hormones, compared to anti-hormones alone,” said Gerd Fastner, MD, of University Hospital, Parcelsus Medical University in Salzburg, Australia in a prepared statement. “This remains true after long-term follow-up of breast cancer patients with a good prognosis. In our analysis the omission of whole breast irradiation turned out to be the main predictor for in-breast recurrences.”
In the study, Fastner and colleagues included 869 women with newly diagnosed, early-stage HR+/HER2-negative breast cancer. Patients had low-risk tumors either grade 1 or 2, less than 3 centimeters and without cancer cells in the lymph nodes. None had received previous chemotherapy, radiotherapy or hormone therapy.
The patients were randomized to receive either WBI (439 women) or anti-hormone treatment (430 women) following breast conserving surgery. Those in the WBI group received a total average dose of 50 GY within six weeks of surgery, and 71% of patients received an additional 10 Gy to the tumor bed.
After 10-year follow-up, Fastner et al. found 10 cases in which cancer recurred in the same breast compared to the 31 patients who received only hormonal therapy.
Additionally, women in the WBI group had a 10-year disease-free survival rate of 94.5% compared to 88.4% in those who received only hormone therapy.
“We believe that the additional benefits of postoperative radiotherapy have been confirmed in hormone receptor positive patients, regardless of whether or not they are at high risk of breast cancer recurrence,” Fastner said in the same statement. “In the light of current knowledge, this does not necessarily mean that they have to have whole breast irradiation nowadays, since partial breast irradiation has proved to be competitive.”